Landsat Helps Guard the World's Forests

By Jon Campbell, U.S. Geological Survey. Fact Sheet 2017–3018, March 2017.

Deforestation near Santa Cruz, Bolivia: 1986 (left) and 2016 (right). USGS Landsat images.

A sentry for the world's forests

"We're seeing the loss of forests in many places," says Matthew Hansen, a professor at the University of Maryland and one of the world's foremost forest watchers. "Dynamics include increasing tropical deforestation, more frequent and severe boreal forest fires, disease in temperate forests and the commoditization of subtropical forests."

Forests are often turned into cropland and pasture, he notes, and that change cuts into what forests provide: benefits for climate and water, and habitat for biodiversity.

The first global map

In 2013, Hansen and colleagues used Landsat 7 data alone to make the first global, high-resolution maps of where trees grew and disappeared. More than 650,000 scenes from 2000–2012, all collected the same way, gave a consistent view across time, borders and ecosystems.

What it showed:

• Most forest lost, in absolute terms: Russia, then Brazil.
• Largest share of forest lost: Malaysia, Cambodia, Côte d'Ivoire, Tanzania, Argentina and Paraguay, among others.
• Fastest-growing loss: Indonesia — its yearly losses in 2011–2012 were twice those of 2000–2003.

Farmer-managed natural regeneration near Rissiam, northern Burkina Faso. Photo: Gray Tappan, USGS.

Holding people to their word

With concern growing, nations and corporations face pressure to prove they are protecting forests. Data from Landsat and other Earth-observing systems can show whether international commitments and corporate sustainability claims are being kept.

Slash-and-burn farming eats into the Upper Guinean forest of Sierra Leone. Photo: Gray Tappan, USGS.

Free data, global view

"This global perspective was only feasible with the existence of free Landsat data," Hansen says. "Landsat represents a public good, Earth-observation infrastructure that allows everyone to study their respective land resources and their change over time."

• Since 1972, Landsat has supplied continuous, objective data used to track water quality, glacier retreat, coral reef health, land-use change, forests and agriculture.
• Who does what: NASA builds the instruments and spacecraft, launches them and checks them in orbit; the USGS owns and operates the satellites and handles reception, archiving, products and distribution.
• Free since 2008: with Interior Department support, the USGS opened its Landsat data to anyone in the world.
• Coverage: Landsat 7 (launched 1999) and Landsat 8 (2013) image the whole Earth every eight days; Landsat 9 was scheduled for late 2020.

Sources

Based on Landsat Eyes Help Guard the World's Forests, by Jon Campbell, USGS Fact Sheet 2017–3018, U.S. Geological Survey; a work of the United States government in the public domain. The import broke off mid-sentence; the rest of that sentence, the Landsat images and the two photographs are taken from the fact sheet's PDF.